I. Field of the Present Invention
The present invention relates generally to apparatus for automatically uncoiling a spool of wire, and more particularly to apparatus for controlling the delivery of the strand from the spool in response to the intermittent operation of the feeder.
II. Description of the Prior Art
Strands of wire are often fed into fabricating machines which bend or stamp the wire into a predetermined shape. During a stamping operation, displacement of the wire strand being fed into the machine is temporarily but repeatedly stopped so that the stamping operation occurs at a predetermined position on the workpiece being formed. Quite often, discrete workpieces are stamped and punched from a supply of wire strand in the form of a coiled spool of wire so that a large supply of the wire strand can be continuously fed into the machining apparatus. While the feeding of wire is normally controlled by a feeder which operates in conjunction with the machining apparatus, for example, pinch rollers aligned to pull the strand into the machine, the inertia of the spool can substantially affect the feeding or displacement of the strand into the machining apparatus. For example, the inertia of the spool may resist the feeding of the strand through the pinch rollers and thus cause slippage between the rollers and the strand which affects the length of the strand being fed into the machining apparatus. Moreover, once the spool has started rotating, intermittent stoppage of the pinch rollers does not immediately affect the momentum of the rotating spool and thus may cause uncontrolled play out of the wire between the deactivated pinch rollers and the coil. Such uncontrolled play out can cause kinking and other uncontrolled deformation of the wire played out between the coil and the feeder.
Some previously known devics for controlling rotation of the coil attempt to actuate and deactuate rotation of the spool by driving the spool in response to play out or actuation and deactuation of the pinch rollers. For example, U.S. Pat. No. 4,269,369 to Stroup and U.S. Pat. No. 4,422,583 to Maxner et al disclose switching apparatus for controlling a powered drive mechanism for the coil. However, such switching devices are complex and require a substantial amount of power to control the heavy spools of wire. Thus, such devices are relatively expensive and require maintenance of a substantial number of components.